Field of the Invention
The invention relates to the field of grips that are used for lifting, pulling, stopping and deployment of objects, particularly heavy objects that are cylindrical in shape, such as umbilical cable, drill pipe, production pipe, power cables etc. More particularly, the invention relates to grips used for such objects in the offshore oil industry.
Discussion of the Prior Art
Umbilical cable, referred to simply as “umbilicals” in the industry, are used in oil and gas operations to provide the necessary control systems, electrical and/or hydraulic power, etc., to the various operations. An umbilical in this type of operation is typically a large cable that encases a plurality of cables or lines, such as flow lines for providing hydraulic fluids and/or chemicals, electrical cables that provide power and controls, and telecommunications cables. The various types of lines and cables may be integrated into a single umbilical or may be provided as separate umbilicals.
The umbilicals reach from the surface, i.e., from a ship or a platform, down to the operation and, thus, may be kilometers long, depending on the depth of the operation. Accordingly, an umbilical being placed into operation weighs many thousands of pounds, which provides a challenge. Conventional gripping systems for an umbilical include a Chinese-finger type grip, such as the grip sold under the band name YALE GRIP. This type of grip includes a plurality of very high tensile rope tails or braids that are integral to a lifting eye at one end and that are individually and contra helically wrapped around the umbilical, such that a grip is formed around the cable. The grip functions as a Chinese finger: when tension is applied to the eye of the grip in the axial direction, the grip extends in length and narrows in the radial direction, thereby creating a firm grip on the umbilical over the length of the applied grip. This type of extended textile grip does not scar or permanently deform the object being lifted.
Often, the size or diameter of an umbilical or pipe may be large and many tons of lifting capacity may be required. One of the drawbacks of the conventional grip is that the rope tails have to be very long (50 to 100 feet or more) to wrap the object, and this requires a significant amount of time, often a number of hours, physical space, and man power to apply the grip and subsequently remove it.
What is needed, therefore, is a grip that can be quickly and easily assembled on the object and subsequently easily removed while also being a grip that is safe and that provides the necessary lifting strength.